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<h2><a name="SECTION0025220000000000000000"></a><a name="doctest-simple-testfile"></a>
<br>
23.2.2 Simple Usage: Checking Examples in a Text
            File
</h2>

<p>
Another simple application of doctest is testing interactive examples
in a text file.  This can be done with the <tt class="function">testfile()</tt>
function:

<p>
<div class="verbatim"><pre>
import doctest
doctest.testfile("example.txt")
</pre></div>

<p>
That short script executes and verifies any interactive Python
examples contained in the file <span class="file">example.txt</span>.  The file content
is treated as if it were a single giant docstring; the file doesn't
need to contain a Python program!   For example, perhaps <span class="file">example.txt</span>
contains this:

<p>
<div class="verbatim"><pre>
The ``example`` module
======================

Using ``factorial``
-------------------

This is an example text file in reStructuredText format.  First import
``factorial`` from the ``example`` module:

    &gt;&gt;&gt; from example import factorial

Now use it:

    &gt;&gt;&gt; factorial(6)
    120
</pre></div>

<p>
Running <code>doctest.testfile("example.txt")</code> then finds the error
in this documentation:

<p>
<div class="verbatim"><pre>
File "./example.txt", line 14, in example.txt
Failed example:
    factorial(6)
Expected:
    120
Got:
    720
</pre></div>

<p>
As with <tt class="function">testmod()</tt>, <tt class="function">testfile()</tt> won't display anything
unless an example fails.  If an example does fail, then the failing
example(s) and the cause(s) of the failure(s) are printed to stdout, using
the same format as <tt class="function">testmod()</tt>.

<p>
By default, <tt class="function">testfile()</tt> looks for files in the calling
module's directory.  See section&nbsp;<a href="doctest-basic-api.html#doctest-basic-api">23.2.4</a> for a
description of the optional arguments that can be used to tell it to
look for files in other locations.

<p>
Like <tt class="function">testmod()</tt>, <tt class="function">testfile()</tt>'s verbosity can be
set with the <b class="programopt">-v</b> command-line switch or with the optional
keyword argument <var>verbose</var>.

<p>
For more information on <tt class="function">testfile()</tt>, see
section&nbsp;<a href="doctest-basic-api.html#doctest-basic-api">23.2.4</a>.

<p>

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